The premium version has a semi-hidden AI suggestion feature. If you double click a word it will select the whole sentence and suggest rewrites that are more formal or shorter. I've found the AI feature great for inspiration.
I use both Grammarly and LT. I wish LT had an option to select the desired tone like Grammarly does. The formal one is occasionally useful but is waaay too formal for regular work-related communications (at least in the US).